1. Field of the Invention
The present invention relates to an intake charge regulating apparatus for an engine including: a throttle body, which includes a throttle bore communicating with an intake port of a cylinder head constituting a part of an engine main body, and in which a throttle valve for controlling the opening of the throttle bore is placed; and a throttle driving mechanism including an electric motor for generating power for driving the throttle valve to open and close, as well as a transmission mechanism for decelerating the driving force of the electric motor, and for transmitting the resultant driving force to the throttle valve.
2. Background Art
Japanese Patent Application No. 2002-256900 discloses a V-type multi-cylinder engine of a type in which an electric motor, for generating power for driving throttle valves to open and close, is arranged in a middle portion between a paired banks.
The V-type multi-cylinder engine of the type disclosed by Japanese Patent Application No. 2002-256900 leads to constructing of an intake charge regulating apparatus in a larger size, because the electric motor is arranged separate from the engine main body.
The present invention has been made with the above-described condition taken into consideration. An object of the present invention is to provide an intake charge regulating apparatus for an engine, which is capable of being constructed in a smaller size.
For achieving the object, the present invention according to a first aspect, is characterized by an intake charge regulating apparatus for an engine including: a throttle body, which includes a throttle bore communicating with an intake port of a cylinder head constituting a part of an engine main body, and which a throttle valve for controlling the opening of the throttle bore is placed in; and throttle driving mechanism including an electric motor for generating power for driving the throttle valve to open and close, as well as a transmission mechanism for decelerating the driving force of the electric motor, and for transmitting the resultant driving force to the throttle valve. The intake charge regulating apparatus is characterized in that: a driven wheel constituting a part of a timing transmission mechanism for transmitting power coming from a crankshaft is fixed to an end portion of a camshaft included in a valve system for driving an intake and exhaust valves to open and close, the intake and exhaust valves being placed in the cylinder head in a way that the intake and exhaust valves are capable of opening and closing; the throttle driving mechanism is arranged in a side which is opposite to the side where the timing transmission mechanism is located in the axis direction of the crankshaft; and the electric motor is arranged between the throttle body and the cylinder head in a plan view.
The present invention according to a second aspect, in addition to the first aspect hereof, is characterized in that: the engine main body is formed into a V4 cylinder engine with a first and second banks which are arranged in a V shape; two throttle bodies including the throttle body are arranged to respectively correspond to two cylinders in the first bank, and the two throttle bodies are connected to each other in order that the two throttle bodies can constitute a first throttle body group; the other two throttle bodies arranged to respectively correspond to two cylinders in the second bank are connected to each other in order that the two throttle bodies can constitute a second throttle body group; the distance between the throttle bores of the two respective throttle bodies in the first throttle body group is set shorter than the distance between the throttle bores of the two throttle bodies in the second throttle body group; and the electric motor is placed in the first throttle body group.
The present invention according to a third aspect, in addition to the second aspect hereof, is characterized in that: the engine main body is mounted on a vehicle body frame of a motorcycle while arranged under an air cleaner and a fuel tank; and the electric motor is arranged under a space created between a cleaner case of the air cleaner and the fuel tank.
It should be noted that a rear bank BR according to an embodiment of the present invention corresponds to the first bank according to the present invention, and a front bank BF, to the second bank according to the present invention. Further, it should be noted that a driven sprocket 48R corresponds to the driven wheel according to the present invention.
The present invention according to the first aspect hereof makes it possible to place the electric motor close to the cylinder head to the maximum possible extent without consideration being given to interference which would otherwise occur between the electric motor and the timing transmission mechanism, and thus, to construct the intake charge regulating apparatus compactly. This is because the throttle driving mechanism is placed in a side which is opposite to the side where the timing transmission mechanism provided between the camshaft of the valve system and the crankshaft is placed in the axis direction of the crankshaft, and also because the electric motor as the throttle driving mechanism is arranged between the throttle body and the cylinder head in a plan view.
In addition, the present invention according to the second aspect hereof makes it possible to effectively arrange the electric motor in the space created by comparatively narrowing down the interval between the two throttle bodies. This is because the interval between the throttle bores of the two respective throttle bodies in the first throttle body group is set shorter than the interval between the throttle bores of the two respective throttle bodies in the second throttle body group, and also because the electric motor is placed in the first throttle body group.
The present invention according to the third aspect hereof makes it unnecessary to devise a scheme of arranging the structural members other than the electric motor in places that are not occupied by the electric motor, and thus, makes it possible to construct the intake charge regulating apparatus compactly. This is because the electric motor is arranged under the space created between the cleaner case of the air cleaner and the fuel tank.